I've never been a coffee drinker — tea is my caffeinated beverage of choice — but my husband is a big fan, so it didn't really come as much of a surprise when our eldest started asking for sips from his cup at an early age. A few years ago, I surveyed friends and coworkers on Facebook and found that many were letting their kids have small amounts of coffee in their tweens and teens. But now that my eldest is a teen, I can see that it won't be long before she starts asking for her own morning cup of joe. So it's time to revisit the question, this time from a more scientific perspective: at what age should kids be allowed to drink coffee?

When it comes to coffee, there are a number of factors to consider. Sure, there's the caffeine to worry about — both the amount in coffee and the additional caffeine that kids get in their diets everyday. There are also calories to consider. Most kids want coffee that's so loaded with cream and sugar that it's more like dessert than a beverage..

Let's start with the caffeine. The average eight-ounce cup of coffee contains about 95 milligrams of caffeine. That amount can be much higher, especially if you're grabbing your coffee on the go. According to the Center for Science in the Public Interest, one 14-ounce bottle of Starbucks Frappuccino contains 130 milligrams of caffeine, a medium (14-ounce) cup of coffee from Dunkin' Donuts contains 210 milligrams, and a regular (16-ounce) cup of Light Roast from Panera contains 300 milligrams.

How much is too much when it comes to kids and caffeine? U.S. health experts recommend a maximum of 400 milligrams per day for adults, but no recommendations have been made for kids. In Canada, where the upper limit for adults is the same as it is south of the border, Health Canada recommends a 45-milligram limit for kids age 4 to 6, 62.5 milligrams for kids aged 7 to 9, and 85 milligrams for kids 10 to 12. The recommended limit for teenagers is 2.5 milligrams per kilogram of body weight.

Following these guidelines, even a small cup of home-brewed coffee would exceed caffeine limits for kids under the age of 12. A teenager would need to weigh at least 84 pounds to handle the 95 milligrams of caffeine in a regular cup.

Of course, all of that assumes that kids have no other source of caffeine in a day. "If it was only coffee that kids drink that has caffeine in it, there would be a simple answer, but kids are getting caffeine in so many other ways that it really is moot to talk about coffee," says Dr. Charles Shubin, director of Pediatrics at Mercy Medical Center in Baltimore.

Caffeine: It's everywhere

A can of soda contains around 40 milligrams of caffeine (more like 54 milligrams if it was a Mountain Dew.) The bottle of Honest Lemon Iced Tea that they downed after school had 90 milligrams, and the can of Monster Energy drink that they had before soccer practice had 160 milligrams. Add some chocolate to the mix in the form of a hot chocolate (25 milligrams) or a chocolate bar (around 9 milligrams) and you can see how quickly it accumulates.

Earlier this year, a 16-year-old boy tragically died from a caffeine overdose after drinking a latte, a soda, and an energy drink. While one cup of coffee may not seem like a big deal, it's important to remember that your child may be getting caffeine from other sources; it can add up quickly.

Here's a look at the caffeine content in some of the foods you might find in your child's daily diet:

Caffeine content chart Source: Data compiled from the Center for Science in the Public Interest.

And what else is in that cup of coffee?

Next up, let's talk about everything else that kids (and adults) generally put into their coffee. By itself, a plain cup of black coffee has about five calories. But every tablespoon of cream added to the cup piles on 51 calories and 5.5 grams of fat while a tablespoon of sugar adds 48 calories. That's how that venti Caramel Frappuccino at Starbucks can add up to 500 calories and 15 grams of fat. That's a lot of fat and calories for a beverage with little nutritional benefit.

But kids around the world drink coffee at a young age, right? Yes, they do, particularly in Scandanavia and Latin America. In Brazil, children are often offered a milky cup of coffee as early as preschool to get them in the habit of drinking a daily cup, and they don't seem to suffer any ill effects. And the old adage that caffeine might stunt your growth is disproved easily with one glance at the children in Norway who grow up perfectly healthy — and often quite tall — on a diet that includes a daily cup.

So at what age should kids be allowed to have coffee? From a scientific perspective, that answer varies depending upon the weight of the child, her personality, and the additional caffeine in her daily diet.

The bottom line is that you'd be hard-pressed to find any data showing that caffeine, and in particular coffee, is good for kids. But while some parents see coffee as a "special treat," some experts, like Dr. Julian Tang of Pediatric Health Associates in Illinois remind parents that the caffeine in coffee is still a drug and it should be treated as such.

"Even though caffeine is readily available and a part of many parents’ diet, it is important to remember that it is a drug which can provide both beneficial and harmful effects," says Tang. "If your child feels tired or dragged down, it’s important to first evaluate their diet and sleep habits. Naturally a cup of coffee is not a substitute for a balanced healthy diet and a good sleep schedule."